A finite amount space is available in a vehicle passenger compartment between the vehicle instrument panel top surface IP and the top of the foot zone FZ in front of a passenger P. As illustrated in FIG. 1, in a prior art ventilation system, the inlet duct ID includes a recirculating air inlet RI and cooperating recirculating inlet doors RD in a top wall TW of the inlet duct, a fresh air inlet FI and cooperating fresh inlet air door FD in a front wall of the inlet duct and an air filter AF. In addition, a blower inlet BI is provided in the bottom wall of the inlet duct ID or top of the scroll fan SF that is driven by the drive motor (not shown).
As further illustrated in FIG. 1, in the prior art design, the panel duct PD, the defroster duct D and the demister duct DD must all be packaged in the relatively confined space provided between the top wall TW of the inlet duct ID and the top surface of the instrument panel IP. As should be further appreciated, a recirculating air clearance zone CZ must also be provided between the panel, defroster and demister ducts PD, D, DD and the recirculating air inlet RI in the top wall TW of the inlet duct ID. Failure to maintain the necessary recirculating clearance zone CZ may compromise airflow into the recirculating air inlet RI. Further, air that is drawn into the recirculating inlet RI that is also forced to pass over and around the panel, defroster and demister ducts PD, D, DD in a circuitous route may generate undesired noise. As a result of the relatively cramped area between the top wall TW of the inlet duct ID and the top surface of the instrument panel IP, it may not always be possible to design the panel duct PD, defroster duct D, and/or demister duct DD to optimum route or size specifications as airflow through the clearance zone CZ into the recirculating inlet RI may become degraded. Consequently, state-of-the-art ventilation systems with a recirculating inlet RI in the top wall TW of the inlet duct ID often represent a series of compromises that generate unwanted noise and/or result in some performance inefficiency.
This document relates to a new and improved ventilation system of lower profile that is able to better accommodate the panel duct PD, defroster duct D and demister duct DD while maintaining free and unrestricted airflow to the recirculating air inlet RI in the inlet duct ID.